Auto Systems and Repair: GM OBD Trouble Code 51
Incorrect MEM-CAL / PROM Error
The PROM and the MEM-CAL basically serve the same function. The PROM was used in earlier model years and the MEM-CAL was used in later model years.
If the ECM detects an internal fault with the PROM or the incorrect MEM-CAl is installed, code 51 will set. The PROM/MEM-CAL is a special "chip" that is installed in the ECM, based on the particular vehicle configuration.
Fault Code Description
- 51 - PROM/Incorrect MEM-CAL
- Engine may not start
- Poor engine performance
- Internal fault with PROM / MEM-CAL
- PROM or MEM-CAL incorrectly installed in ECM